Tear strip structure for cans



g- 1954 J. 5. ARMSTRONG TEAR STRIP STRUCTURE FOR CANS Filed Nov. 19, 1962 2 Sheets-Sheet 1 INVENTOR BY I" ATTORNEYS 1964 J. 5. ARMSTRONG 3,144,955

TEAR STRIP STRUCTURE FOR CANS Filed Nov. 19, 1962 2 Sheets-Sheet 2 INVENTOR Jnmfl). S. ARMSTRONG ATTORNEZS United States Patent 3,144,955 "HEAR srmr STRUCTURE FUR CANS James Sidney Armstrong, Bernal, Euenos Aires, Argein tiua, assignor to Compania wift de la Plato Sociedad Auonima Frigorifiea, Buenos Aires, Argentina Filed Nov. 19, 1962, Ser. No. 238,351 Glaims priority, application Australia Nov. 27, 1961 9 Claims. (Cl. 22 9-54) The present invention refers to improvements in cans used for canned goods and more particularly to tear strips in tapered cans and the like, wherein said tear strip forms part of a single side wall can and has a tongue, so that the can may be opened by means of a key.

The known cans of this type have usually a pair of parallel score lines defining the tear strip, so that upon opening the can by means of the key special attention has to be payed to move the key always in such a way that the tear strip does not tend to move out of said score lines, otherwise it quite often happens that either the tear strip breaks before having been torn around the entire periphery of the can or move out of one of the score lines defining the limit of the preview tear strip path, whereupon the actual tear strip path cannot be controlled and since usually the key stems are rather short, the arbitrary movement of such a strip does not permit to open the can with such a key.

If it is borne in mind that the thickness of the tin plate is rather small, and that the score lines should not enter more than approximately half the thickness of the tin plate, because otherwise there is a tendency that the tin plate will crack during the canning process of the goods, particularly if meat products are used which have to be cooked afterwards in the can, it will be apparent to those skilled in the art, that it happens that the score lines sometimes are not sufficiently deep so as to assure a correct guiding of the tear strip. It also happens that the tools, such as the scoring rolls, get Worn out and thereby the scoring lines are not properly and in a perfect continuous manner performed so that, on the finished can the score lines are not continuous, which again makes it difiicult to open such a can.

To overcome these drawbacks, it has already been proposed to form each limit line of the parallel lines which will define the tear strip by a pair of parallel adjacent score lines, but although this has somewhat improved, the conditions, it has not provided a perfect system, because if one of the score lines is imperfect it has been found in practice that once the tear strip gets out of its normal path, that then the second score line very seldomly retains or returns the tear strip towards its predetermined path. To this it has to be added that often the failure in the proper scoring is due to the fact that the thickness, physical or chemical constitution of the tin plate is not uniform and that the granular arrangement in some portions, due to tensions, provide either deeper or shallower score lines as they should be.

Furthermore, in so called collar cans, wherein the tear strips are defined by parallel score lines which surround the cans adjacent the upper end closures thereof, and where a collar is mounted in the upper end of each can opposite its tear strip in position for extending upwardly from the upper extremity of the can body resulting from the tearing out of the strip, thereby to maintain the desired can body Wall height and provide a support neck over which the skirt or body wall portion remaining attached to the upper end closure can be telescoped to effect a reclosure of the can, the thickness of the tin plate used is larger, so that the depth of the scoring lines may likewise be more pronounced and therefore the above outlined problem does not exist in such an outstanding way.

In this type of cans it has been proposed to provide between the parallel score lines at least three parallel spaced rib means extending about the wall within the entire area that confines the tear strip, wherein the amount of ribs is usually three of which, two outer ribs are projecting in one direction from the Wall cross section and the intermediate rib projects in the opposite direction, to provide cooperating rib and groove means effective to nest and prevent side slipping of the tear strip, as it: is wound about a key in the process of being torn out of the wall. In this embodiment, although quite effective for what it is sought, the tear strip as such is reinforced and would not be suitable in a can of the type of the present invention.

According to the present invention the tear strip as such in its major portion remains flat. Only in the marginal zones of the score lines, which in this embodiment consist at each margainal Zone of a pair of parallel score lines, a head is provided between said score lines, which bead may either be embossed or rolled, so that the grains of the metal in that portion are changed With regard to the grains of the metal in the middle major portion of the tear strip. Thus, even if the pairs of score lines are not prefect, the combination of the pairs of score lines and the beads in between, assure that the predetermined path is maintained during opening of the can.

In other words, what assures the correct guiding of the tear strip is that at its margainal portions the shape of the tin is changed. This provides an additional tear guide, particularly if it is borne in mind that such a change of shape exerts an influence on the granularity of the tin plate. To this end, it may be added that the granularity of the pin plate is not always uniform and therefore the scoring action is preferably carried out in the rolling direction of the tin plate. It is to be pointed out that upon changing the shape either by beading or rolling, a reorganization of the grains takes places within the tin plate, which provides the additional advantage sought.

The beads may either project out of the outer surface of the can or be directed towards the chamber defined by the can and the number of beads at each marginal line may be increased if the number of score lines is increased.

The shape of the bead as such may vary, depending mainly on the type of tin used and particularly a different result is obtained when the beads are molded whereby the thickness of each bead is constant, or when the beads rolled whereby the apex portion of each head is thinner than the side Wall portions of said bead.

Thus, the present invention consists in a can having a body wall with at least two pairs of parallel score lines defining the marginal portions of a tear strip having a major flat middle portion, and wherein between said pairs of score lines the body Wall is embossed.

The present invention may likewise be defined as a can manufactured of metal sheets having a first base, a second base and a side wall surrounding said bases, two pairs of parallel score lines adjcent one of said base portions, said score lines defining an endless path in said side wall, an endless bead between each pair of score lines, a flat portion between said two pairs of score lines, said fiat portion being larger in width than said beads, and said beads projecting out of the plane defined by said side wall containing said fiat portion.

With the above in view, the nature of the invention will be more clearly understood by reference to the following detailed description of the preferred structural embodiments, which are disclosed by way of example in relationship to the accompanying drawings, wherein:

FIGURE 1 shows in perspective view a tapered can of the type used for corned-beef and the like, in accordance with the present invention.

aliases FIGURE 2 is a perspective view of a portion of a machine for carrying out the manufacturing process of scoring and beading the tear strip.

FIGURE 3 is a plan view of a part of the machines, schematically shown in FIGURE 2.

FIGURE 4 is a front elevation, partially in section, of a pair of scoring rolls.

FIGURE 5 is a front elevation, of a pair rolls.

FIGURE 6 is a cross section of a portion of the finished tin plate manufactured with the rolls as shown in FIGa URES 4 and 5.

FIGURE 7 is a detail in front elevation, partially in section, of a pair of rollers which at the same time roll the beads changing the thickness of the tin plate.

It may be appreciated in FIGURE 1 where a tapered can 1 manufactured of metal sheet is shown which is the type which is usually used for corned-beef, that the can 1 comprises a smaller base 2, a larger base 3 and a sidewall 4. In a portion near the larger base 3, two pairs of parallel score lines 5, 5 and 6, 6' define between each of them a bead '7 with a flat portion 21 in the middle. The assembly is a tear strip 26, which is to be torn off from the wall 4 in order to open the can I, as is already known in the art. For tearing the tear strip 26, a key 3 is usually provided which in the front portion of the stem 9 is usually fiat and has a slot it into which a tongue (not visible) which projects out of the tear strip 26 enters, so that upon rotating the key S the tear strip 26 is torn off the side wall 4.

The score lines 5 and 6 (alone) which as such are well known, have the drawback that they are not always perfectly drawn, for the reasons as above outlined and in that event the tear strip 236 breaks before having completely opened the can 1.

As to the preferred embodiment of the tear strip 26, according to the present invention, which is still flat in its major portion and more particularly in the middle portion 21 or 21' (see FIGURES 6 and 7, respectively), the marginal portions are each provided with a V-shaped bead 7 the apex of which may be directed in either direction as previously stated, although in practice it is preferred that the apex is directed towards the chamber defined by the can ll. This change of shape in the mar ginal portions provides the additional guiding means when the tear strip 26 is torn off, as previously explained.

Tests have been made and have shown that it is even possible to more or less correctly tear off the strip with a pair of these beads in the marginal portions, although the score lines are not present.

However, in practice the score lines 55, 5 and 6, a and the beads 7 should be used, thereby providing a further safety factor for correctly opening the can.

In other words, it is an important aspect that in the larger middle portion of the strip which in FIGURE 6 is identified by reference numeral 21 and in the alternative embodiment of FIGURE 7 by reference numeral 21, which will be later described, the shape of the original tin plate is not changed and therefore the tensions and granular structure is likewise not changed. A change is made in the marginal portions where the V-shaped beads 7 exist, so that there, the granular structure is changed in benefit of the tearing action. In addition, it is to be borne in mind that in this type of can, where the meat is cured after the can has been closed or similar processes are carried out with the closed can, the score lines should not be too deep, since otherwise there is a tendency of cracking during the curing or what other process is carried out in the latter step of the processing. In those cans where portions of the score lines are not sufficiently deep the V shaped beads will assure that nevertheless the tearing action will be perfect. This is of course a completely different problem as the one which exists in cans made of thicker tin plate, where the score lines may f beading always be suficiently deep to assure the correct guiding of the tear strip during the tearing action.

As shown in FIGURES 2 and 3 the machine used for scoring and beading the tin plate 11 which will later on define the side wall 4, consists of a plurality of complementary rollers which in this particular case are located on a curved path, bearing in mind that the tin plate 11 will have to define a side wall 4 of a tapered can 1. The pairs of rollers may either be arranged in such a way as to provide first the embossing or rolling action to define the beads and thereafter the scoring action or vice versa.

In the embodiment shown in FIGURE 2, the tin plate Ill is moved forward in the direction as indicated by arrow I2, so that in first instance the plate 11 passes through a pair of scoring rolls 13 and 14, and thereafter through a pair of embossing rolls I5 and 16.

The pair of scoring rolls 13 and 14 consists of a male scoring roll 14 having as two pairs of scoring knives 17, 17' (see FIGURE 4), which are conveniently spaced apart so as to provide the necessary space for the beads and which knives 17, ll?" operate in cooperation with two paris of recesses 13, 18 of the female scoring roll 13. When the tin plate 11 leaves said pair of scoring rolls 13 and 14, it will be provided on one of its faces with the scores 5, 5 and 6, 6. The scores 5 and 6 (FIGURE 6) will define the marginal portions of the tear strip blank. Each of the score lines may, if desired be scored by sep-' arate pairs of rolls.

Once these two pairs of score lines 5, 5 and 6, 6 are made upon the tin plate 11 carrying on its movement (FIGURE 3) in the direction of arrow 12, it will pass through a pair of embossing rolls I5 and 16 (FIGURE 2). The pair of embossing rolls and 16 again consists of a male embossing roll 16, having two embossing projections I) (FIGURES 2, 3 and 5) and a female roll 15 having complementary recesses 29. Each embossing ring or projection 1'9 and complementary recess 20 are arranged in a position so that upon the tin plate 11 leaving said pair of embossing rolls 15 and 16, there is between each of the pair of score lines 5, 5' and 6, 6' a bead 7 (FIGURE 6) which is usually concave V shaped.

Similarly, each head may be made in a separate pair of rolls.

In the embodiment shown in FIGURE 7, which is prefr erably used with tin plate of slightly larger thickness or where the granular structure defines a harder material, it is advisable that instead of using the embossing rolls, actual rollers are used, consisting of the male roller 22 and the female roller 23, wherein the male roller has the rolling and embossing projections 24 which operate in combination with the recesses 25 of the female roller 23, thereby providing between each pair of score lines 5, 5' and 6, 6' a rolled embossed portion 7' which in the apex portions are reduced in width whereby the tearing action is again facilitated. There again between the pair of inner score lines 5' and 6', the main portion 21' of the tear strip is flat.

Within the above defined concepts certain additional modifications may be suggested, for instance each of the score lines 5, 5' and 6, 6' may be replaced by two adjacent score lines in the event that the existing type of machine is used.

I claim:

1. A can with a tear strip having a body wall, at least two pairs of parallel score lines in said body wall and defining the marginal portions of said tear strip, said tear strip having a major fiat middle portion, each pair of said parallel score lines defining in between them an embossed portion.

2. A can manufactured of metal sheet having a first base, a second base and a side wall surrounding said bases, two pairs of parallel score lines adjacent one of said base portion, said score lines defining an endless path in said side wall, an endless bead between each pair of score lines, a fiat portion between said two pairs of score lines, said flat portion being larger in width than said beads, and said beads projecting out of the plane defined by said side wall containing said flat portion.-

3. A can as claimed in claim 2, wherein said score lines are continuous.

4. A can as claimed in claim 3, wherein said score lines are intermittent.

5. A can as claimed in claim 2, wherein said score lines enter approximately half the thickness of the metal sheet of said side wall.

6. A can as claimed in claim 2, wherein said beads are V shaped.

7. A can as claimed in claim 6, wherein said beads are of uniform thickness.

6 8. A can as claimed in claim 6 wherein the apices of said beads are of smaller thickness than the remaining portions of said beads.

9. A can as claimed in claim 6, wherein said beads are outwardly embossed with regard to the chamber defined by said can.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE @ERTIFICATE OF CORRECHN F'aLent Noe 3 144355 Au usi re 19641 James Sidney Armstrong It is hereby certified that error appears in the above numbered paten't requiring correction and that the said Letters Patent should read as corrected below.

In the grant, lines 2 and 12,, and in the heading to the printed specification, line 4, for "Plato", each oocurrence read Plate --u Signed and sealed this 1st day of December 1964,

(SEAL) Auesi:

ERNEST W0 SWIDER EDWARD J. BRENNER. Attesting Officer Commissioner of Patents 

2. A CAN MANUFACTURED OF METAL SHEET HAVING A FIRST BASE, A SECOND BASE AND A SIDE WALL SURROUNDING SAID BASES, TWO PAIRS OF PARALLEL SCORE LINES ADJACENT ONE OF SAID BASE PORTION, SAID SCORE LINES DEFINING AN ENDLESS PATH IN SAID SIDE WALL, AN ENDLESS BEAD BETWEEN EACH PAIR OF SCORE LINES, A FLAT PORTION BETWEEN SAID TWO PAIRS OF SCORE LINES, SAID FLAT PORTION BEING LARGER IN WIDTH THAN SAID BEADS, AND SAID BEADS PROJECTING OUT OF THE PLANE DEFINED BY SAID SIDE WALL CONTAINING SAID FLAT PORTION. 